This invention relates generally to the mounting of microwave circuits in housings. More particularly, the present invention relates to making right angle microwave connections to the housing to supply signals to microwave circuits on a carrier.
Typically many microwave circuits or individual components make up a subsystem enclosed within a single housing. The components may include amplifiers, couplers, switches, detectors, transmission lines, matching circuits or MMICs which may include any or all of the proceeding. Most of these components must be mounted to ground. Such mounting can be accomplished using solder or conductive epoxy to attach the components to the metal housing.
It may also be desired to mount individual components, or a small group of components or MMICs, on a metal carrier to provide the ground. A carrier is a thin piece of metal, typically xc2xd to 1 mm thick, which provides the ground for the circuits. An undesirable feature with carriers is that at high frequencies, such as microwave frequencies, the ground normally formed by the thickness of the carrier at lower frequencies provides an electrical discontinuity that can approach a full reflection at millimeter wave frequencies if full contact is not maintained between the carrier and housing.
Carriers which can provide grounding at high frequencies become more desirable with the increasing availability of MMIC subsystems. If a number of MMICs are mounted directly onto a housing and one of them fails, the entire assembly must be discarded, as it is generally impossible to remove a fragile MMIC after it has been mounted without destroying other MMICs in the vicinity. However, a carrier can be mechanically placed in and removed from the housing without destroying the circuit components mounted on it.
Once circuit components are mounted on a carrier, it is necessary to make connections between the carrier and the outside world. This is frequently accomplished using a coaxial connector. It is critical to maintain a good ground between the outer conductor of the coaxial cable supplying a signal to the coaxial connector and the carrier. It is also desirable to minimize the area required to make a connection between the coaxial cable and the carrier. However, as shown in FIG. 1A, a standard coaxial cable connector 4 occupies a large area.
In accordance with the present invention, a coaxial cable right angle connection is used to make a high-frequency electrical connection between microwave integrated circuit components in a housing and the outside world. A carrier is mounted within the housing, and provides grounding for attached microwave components. A coaxial cable extends through a sleeve, which is contained within the housing. The sleeve is soldered to the coaxial cable and is maintained against the carrier using an axial screw, thereby assuring good grounding from the outer conductor of the coaxial cable to the carrier. A bore is provided through the carrier for the coaxial cable and is counterbored to form first and second bores with different diameters. The outer conductor of the coaxial cable is removed for insertion through the carrier and the dielectric provided within the coaxial cable extends through the first bore in the carrier. A center conductor of the coaxial cable extends through both bores in the carrier to a point adjacent microwave components mounted on the carrier. The dielectric of the coaxial cable is removed so that the center conductor alone extends through a portion of the second bore to form an air dielectric section. The center conductor of the coaxial cable can be attached to microwave components mounted to the carrier using ribbon bonding.